JP2790079B2 - Oxide superconducting circuit - Google Patents
Oxide superconducting circuitInfo
- Publication number
- JP2790079B2 JP2790079B2 JP7149982A JP14998295A JP2790079B2 JP 2790079 B2 JP2790079 B2 JP 2790079B2 JP 7149982 A JP7149982 A JP 7149982A JP 14998295 A JP14998295 A JP 14998295A JP 2790079 B2 JP2790079 B2 JP 2790079B2
- Authority
- JP
- Japan
- Prior art keywords
- superconducting
- region
- line
- concave region
- superconducting line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Measuring Magnetic Variables (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、段差部を有する絶縁体
と、これに接して形成された酸化物超電導体からなる超
電導薄膜とを含んで構成され、この段差部が超電導弱結
合部として機能する段差型ジョセフソン接合を含んだ酸
化物超電導回路の構成に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an insulator having a step portion and a superconducting thin film made of an oxide superconductor formed in contact with the step portion, and the step portion serves as a superconducting weak coupling portion. The present invention relates to a configuration of an oxide superconducting circuit including a functioning step-type Josephson junction.
【０００２】[0002]
【従来の技術】従来、段差型ジョセフソン接合を用いた
応用については、アップライド フィズィックス レタ
ー 第６０巻 １９９２年 第３０４８頁から第３０５
０頁(Applied Physics Letters 60 (1992) 3048-3050)
に記載されている。2. Description of the Related Art Conventionally, an application using a step-type Josephson junction is described in Applied Fizzix Letter, Vol. 60, 1992, pp. 3048 to 305.
Page 0 (Applied Physics Letters 60 (1992) 3048-3050)
It is described in.
【０００３】[0003]
【発明が解決しようとする課題】上記従来技術は段差型
ジョセフソン接合を用いてdc ＳＱＵＩＤ(Superconduct
ing Quantum Interference Device；超電導量子干渉素
子)を作製した例である。上記文献Ｆig.1に示されてい
るように、絶縁体としてＳrＴiＯ3またはＬaＡlＯ3絶縁
性基板を用い、その表面に凹部領域を形成している。凹
部領域の深さは０.３〜０.４μｍであり、凹部領域とそ
うでない領域の境界は段差部となる。凹部領域は基板半
平面全体に亘って形成されているので段差部すなわち境
界は基板中央に一直線状に配置されている。段差高さは
凹部領域の深さ０.３〜０.４μｍに一致する。この基板
上にＹＢa2Ｃu3Ｏx酸化物超電導体からなる超電導薄膜
が形成されている。膜厚は段差高さより低い１５０ｎｍ
である。この超電導薄膜は超電導線路を含んでおり、こ
の超電導線路は段差部を２箇所で乗り越えているが、凹
部領域を横断していない。これら超電導線路の段差部は
いずれも超電導弱結合部、すなわちジョセフソン接合と
して機能している。この従来例はジョセフソン接合を２
つ含む例であるが、２つ以上の多くのジョセフソン接合
を含んだ複雑な超電導回路を作製する試みはなされてい
ない。従って多数のジョセフソン接合を含む超電導回路
を実現する際の問題点が考察されていない。段差型ジョ
セフソン接合を含んだ超電導回路では、段差部は凹部領
域とそうでない領域の境界に形成されるため、元々任意
の位置にジョセフソン接合を配置することが困難である
という問題を有するが、さらに超電導薄膜が段差部を乗
り越える時に常にジョセフソン接合が形成されるため凹
部領域とそうでない領域をジョセフソン接合を含まない
超電導線路、すなわち超電導配線で接続することがむず
かしいという問題を有する。従って上記従来例のように
凹部領域を基板半平面全体という広い領域に亘って形成
すると複雑な超電導回路を作製する際、レイアウト設計
に大きな制約を加えることになる。The above prior art uses a step-type Josephson junction to form a dc SQUID (Superconductor).
This is an example of fabricating a superconducting quantum interference device (ing Quantum Interference Device). As shown in the above document FIG. 1, a SrTiO 3 or LaAlO 3 insulating substrate is used as an insulator, and a concave region is formed on the surface thereof. The depth of the concave region is 0.3 to 0.4 μm, and the boundary between the concave region and the other region is a step. Since the concave region is formed over the entire half-plane of the substrate, the step, that is, the boundary, is arranged in a straight line at the center of the substrate. The height of the step corresponds to a depth of 0.3 to 0.4 μm of the concave region. A superconducting thin film made of a YBa 2 Cu 3 Ox oxide superconductor is formed on the substrate. The film thickness is 150 nm, which is lower than the step height
It is. The superconducting thin film includes a superconducting line. The superconducting line climbs over the step at two places but does not cross the recessed region. Each of the step portions of these superconducting lines functions as a superconducting weakly-coupled portion, that is, a Josephson junction. This conventional example uses two Josephson junctions.
However, no attempt has been made to fabricate a complex superconducting circuit that includes two or more Josephson junctions. Therefore, no problem has been considered in realizing a superconducting circuit including a large number of Josephson junctions. A superconducting circuit including a step-type Josephson junction has a problem that it is difficult to arrange a Josephson junction at an arbitrary position from the beginning because the step is formed at the boundary between the recessed region and the other region. Further, since a Josephson junction is always formed when the superconducting thin film gets over the step, there is a problem that it is difficult to connect the recessed region and the other region with a superconducting line not including the Josephson junction, that is, a superconducting wiring. Therefore, when the concave region is formed over a wide region of the entire substrate half-plane as in the above-mentioned conventional example, a large constraint is imposed on the layout design when a complicated superconducting circuit is manufactured.
【０００４】この問題を解決するための方法の１つは、
凹部領域を比較的大きな面積としたまま、凹部領域とそ
うでない領域の境界である段差部を超電導弱結合として
ではなく、超電導配線として乗り越えることであり、こ
のためには以下の２つの手段が考えられる。[0004] One way to solve this problem is to:
In this case, the stepped portion, which is the boundary between the recessed region and the region other than the recessed region, is overcome as superconducting wiring, not as superconducting weak coupling, with the relatively large area of the recessed region. Can be
【０００５】第１の手段は、段差部を乗り越える超電導
薄膜の性質が、段差の高さ、段差の角度に依存すること
に注目する。すなわち、段差の高さが高く、角度が急峻
であるほどその超電導性は弱められ、超電導弱結合部が
形成され、従ってこの箇所はジョセフソン接合として機
能する。一方、２つの領域を超電導配線で接続するため
には、接合部の超電導性を強める必要がある。従って段
差部で分けられた凹部領域とそうでない領域の２つの領
域をある箇所ではジョセフソン接合として、またある箇
所では超電導配線として接続するためには、段差の高
さ、段差の角度を接続箇所によって変え、結合の強さを
調整すればよい。しかし、この手段では段差作製のため
に多数の工程を要してしまう。[0005] The first means pays attention to the fact that the property of the superconducting thin film over the step depends on the height of the step and the angle of the step. That is, as the height of the step is higher and the angle is steeper, the superconductivity is weakened, and a superconducting weak coupling portion is formed, and thus this portion functions as a Josephson junction. On the other hand, in order to connect the two regions with the superconducting wiring, it is necessary to increase the superconductivity of the joint. Therefore, in order to connect the two regions, that is, the recessed region divided by the step portion and the region that is not so, as a Josephson junction at a certain place and as a superconducting wiring at a certain place, the height of the step and the angle of the step are determined at the connection point. And the strength of the bond may be adjusted. However, this means requires a number of steps for producing steps.
【０００６】第２の手段は、接続の配線幅を広くし、最
大超電導電流値を他のジョセフソン接合部よりも大きく
し、これより弱結合特性が現れないようにすることであ
る。しかし、この手段では、配線の占める面積が大きく
なり、集積性が損なわれるという問題が生じる。The second means is to increase the wiring width of the connection and to make the maximum superconducting current value larger than that of other Josephson junctions so that weak coupling characteristics do not appear. However, in this means, there is a problem that the area occupied by the wiring is increased, and the integration is impaired.
【０００７】本発明の第１の目的は、レイアウト設計上
の制約を緩和し、かつ工程数や集積性を著しく損なわず
に、多数の段差型ジョセフソン接合を含んだ複雑な酸化
物超電導回路を実現することにある。A first object of the present invention is to provide a complex oxide superconducting circuit including a large number of step-type Josephson junctions without alleviating restrictions on layout design and without significantly reducing the number of steps and integration. Is to make it happen.
【０００８】本発明の第２の目的は、良好な素子特性を
実現することにある。A second object of the present invention is to realize good device characteristics.
【０００９】[0009]
【課題を解決するための手段】上記課題を解決するため
に、本発明の酸化物超電導回路は、基板上に形成された
絶縁性薄膜または絶縁性基板自体からなる絶縁体と、該
絶縁体に接して形成された酸化物超電導体からなる超電
導薄膜とを少なくとも含んで構成され、該絶縁体は表面
に少なくとも１つ以上の凹部領域を含み、該超電導薄膜
は少なくとも１つ以上の超電導線路を含み、かつ該超電
導線路は該凹部領域とそうでない領域の境界と２箇所以
上で交わり、該超電導線路は該凹部領域を横断して２つ
以上の領域に分割していることを特徴とするものであ
る。In order to solve the above-mentioned problems, an oxide superconducting circuit according to the present invention comprises an insulator made of an insulating thin film or an insulating substrate itself formed on a substrate, and an insulator formed of the insulating substrate itself. And a superconducting thin film made of an oxide superconductor formed in contact with the insulator. The insulator includes at least one or more recessed regions on the surface, and the superconducting thin film includes at least one or more superconducting lines. And the superconducting line intersects at least two places with the boundary between the concave region and the other region, and the superconducting line is divided into two or more regions across the concave region. is there.
【００１０】さらにまた、上記課題を解決するために、
本発明の酸化物超電導回路は、上記凹部領域の深さは１
μｍ以下、かつ該凹部領域と上記超電導線路の交わりは
該超電導線路に沿って長さ２μｍ以下であることを特徴
とするものである。Further, in order to solve the above-mentioned problems,
In the oxide superconducting circuit of the present invention, the depth of the concave region is 1
μm or less, and the intersection of the concave region and the superconducting line has a length of 2 μm or less along the superconducting line.
【００１１】[0011]
【作用】段差部を境界として絶縁体表面は凹部領域とそ
うでない領域に分けられる。超電導線路はこの境界と２
箇所以上で交わり、この凹部領域を横断して凹部領域を
２つ以上の領域に分割している。すると、この交点はジ
ョセフソン接合となるので、超電導線路に沿ってジョセ
フソン接合の直列接続体が形成されることになる。ジョ
セフソン接合の直列接続体は特性値のバラツキを増大さ
せる要因となり、必ずしも望ましくはないが、出力電圧
を直列接続の数だけ倍増させる以外に、特に素子動作に
影響を及ぼすことはない。従って、この凹部領域の面積
を十分小さくして、絶縁体の表面の所望の位置に配置
し、ジョセフソン接合を形成したい超電導線路は、この
凹部領域を横断し、凹部領域を２つ以上の領域に分割す
るように配置し、超電導配線を形成したい超電導線路
は、この凹部領域を横断しないように迂回して配置すれ
ば、レイアウト設計に何らの制約も加えずに、ジョセフ
ソン接合と超電導配線を同時に得られることになる。但
し、たとえ絶縁体表面に凹部領域を形成し、超電導線路
をこの凹部領域と交わるように形成したとしても、この
超電導線路がこの凹部領域を２つ以上の領域に分割しな
ければ、超電導線路の幅を横切ってジョセフソン接合は
形成されない。従って、ジョセフソン接合を形成する超
電導線路は、凹部領域を２つ以上の領域に分割すること
が必要である。また本発明の回路を作製する工程数は上
記従来例より何ら増加することはない。さらに、凹部領
域の面積を十分小さくすれば集積性を著しく損なうこと
もない。従って、これよりレイアウト設計上の制約を緩
和し、かつ工程数や集積性を著しく損なわずに、多数の
段差型ジョセフソン接合を含んだ複雑な酸化物超電導回
路を実現でき、上記本発明の第１の目的を達成できるこ
とになる。The surface of the insulator is divided into a concave region and a non-concave region with the step portion as a boundary. The superconducting line is at this boundary and 2
Intersecting at more than one point, the concave region is divided into two or more regions across the concave region. Then, since this intersection is a Josephson junction, a series connection of the Josephson junction is formed along the superconducting line. A Josephson junction series-connected body causes a variation in characteristic values and is not always desirable, but does not particularly affect the operation of the element except for doubling the output voltage by the number of series connections. Therefore, the superconducting line for which the area of the concave region is sufficiently reduced to be arranged at a desired position on the surface of the insulator and a Josephson junction is to be formed crosses the concave region and the concave region is divided into two or more regions. The superconducting line on which the superconducting wiring is to be formed is detoured so as not to cross this recessed region, and without adding any restrictions to the layout design, the Josephson junction and the superconducting wiring can be formed. Will be obtained at the same time. However, even if a concave region is formed on the insulator surface and the superconducting line is formed so as to intersect with the concave region, the superconducting line is not divided unless the superconducting line divides the concave region into two or more regions. No Josephson junctions are formed across the width. Therefore, in the superconducting line forming the Josephson junction, it is necessary to divide the concave region into two or more regions. Further, the number of steps for manufacturing the circuit of the present invention does not increase at all from the conventional example. Furthermore, if the area of the concave region is made sufficiently small, the integration is not significantly impaired. Therefore, a complicated oxide superconducting circuit including a large number of step-type Josephson junctions can be realized without alleviating the restriction on the layout design and without significantly impairing the number of steps and integration. The first purpose can be achieved.
【００１２】凹部領域の面積を小さくすることは、集積
性を向上させるために有効であるが、さらに良好な素子
特性を実現するという効果ももたらす。すなわち、段差
型ジョセフソン接合では、絶縁体は上面、下面及び有限
の角度で形成された段差の斜面からなり、さらに酸化物
超電導体からなる超電導薄膜がこの絶縁体に接して形成
されるが、この超電導薄膜の配向軸は段差の上面と下面
では同じであるが、段差の斜面ではこれと異なる。従っ
て、段差の上端および下端では配向軸が異なることによ
り粒界が形成され、これがジョセフソン接合となる。こ
のため、凹部領域の面積が大きく、凹部領域と超電導線
路の交わる領域の長さが十分長い場合には、超電導線路
と上記閉ループの交点２箇所それぞれにおいて、段差の
上端および下端に粒界が形成され、ジョセフソン接合の
直列接続体が形成されることになる。一方、段差の角度
を９０°未満として、凹部領域の面積を十分小さくし、
凹部領域と超電導線路の交わる領域の超電導線路の進行
方向に沿った長さを十分短くすれば、段差の斜面が近接
して対向し、下面は近似的に無視することができる。こ
の時、上面と斜面のみ存在することになるので、粒界は
近接して対向した２つの斜面の上端に形成され、直列接
続ではない単一のジョセフソン接合が得られることにな
る。実際、この凹部領域と超電導線路の交わる領域の超
電導線路の進行方向に沿った長さを２μｍ以下とし、凹
部領域の深さを１μｍ以下とすればこの構造を実現する
ことができる。これより直列接続体ではなく単一のジョ
セフソン接合が得られ、特性値のバラツキが抑えられ、
従って、良好な素子特性を実現できるので、上記本発明
の第２の目的を達成できることになる。Reducing the area of the recessed region is effective for improving the integration, but also has the effect of realizing better device characteristics. That is, in the step-type Josephson junction, the insulator consists of an upper surface, a lower surface, and a slope of a step formed at a finite angle, and a superconducting thin film made of an oxide superconductor is formed in contact with the insulator. The orientation axis of the superconducting thin film is the same on the upper surface and the lower surface of the step, but is different on the slope of the step. Therefore, a grain boundary is formed due to different orientation axes at the upper end and the lower end of the step, and this forms a Josephson junction. Therefore, when the area of the concave region is large and the length of the region where the concave region and the superconducting line intersect is sufficiently long, grain boundaries are formed at the upper and lower ends of the step at each of two intersections of the superconducting line and the closed loop. Thus, a series connection of Josephson junctions is formed. On the other hand, by setting the angle of the step to less than 90 °, the area of the concave region is made sufficiently small,
If the length of the region where the concave region intersects with the superconducting line along the traveling direction of the superconducting line is made sufficiently short, the slopes of the steps are close to face each other, and the lower surface can be approximately ignored. At this time, since only the upper surface and the slope are present, the grain boundary is formed at the upper end of the two slopes that are close to each other and a single Josephson junction that is not connected in series is obtained. Actually, this structure can be realized if the length of the region where the concave region intersects with the superconducting line along the traveling direction of the superconducting line is 2 μm or less and the depth of the concave region is 1 μm or less. As a result, a single Josephson junction is obtained instead of a series connection, and variations in characteristic values are suppressed.
Therefore, good device characteristics can be realized, and the second object of the present invention can be achieved.
【００１３】[0013]
【実施例】本発明の内容を以下実施例を用いて詳細に説
明する。図１及び図２を用いて第１の実施例を説明す
る。本実施例は、酸化物超電導回路としてＱＦＰ(Quant
um Flux Parametron；量子磁束パラメトロン)を作製し
た例である。DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described in detail below with reference to embodiments. A first embodiment will be described with reference to FIGS. In this embodiment, a QFP (Quantum
um Flux Parametron (quantum flux parametron).
【００１４】図１はＱＦＰのレイアウト図である。但し
励振線を省略して記述している。(１００)ＳrＴiＯ3基
板からなる絶縁体１の表面に長方形ＡＢＣＤの凹部領域
２を形成した。凹部領域の深さ、すなわち段差の高さは
ｈ＝０.３μｍ、線分ＡＢ、線分ＤＣの長さは共に１μ
ｍ、線分ＡＤ、線分ＢＣの長さは共に８μｍである。段
差は通常の有機レジスト、光リソグラフィ、Ａrイオン
ビームエッチングを用いて作製した。FIG. 1 is a layout diagram of a QFP. However, the excitation line is omitted in the description. A rectangular ABCD recessed region 2 was formed on the surface of an insulator 1 made of a (100) SrTiO 3 substrate. The depth of the concave region, that is, the height of the step is h = 0.3 μm, and the length of each of the line segment AB and the line segment DC is 1 μm.
The length of each of m, line segment AD, and line segment BC is 8 μm. The steps were formed using ordinary organic resist, photolithography, and Ar ion beam etching.
【００１５】この絶縁体１の上に酸化物超電導体ＹＢa2
Ｃu3Ｏxからなり、膜厚０.２μｍの超電導薄膜を形成し
た。さらにエッチング加工により図１に示した超電導線
路３を形成した。凹部領域とそうでない領域の境界、す
なわち長方形ＡＢＣＤの周囲は段差が形成されており、
超電導線路４はこの境界と交点５、６の２箇所で、超電
導線路７は交点８、９の２箇所で交わる。従って、２つ
の超電導線路４、７はいずれも凹部領域２を横断してお
り、凹部領域２を３つの領域に分割している。従って交
点５、６、８、９では、ジョセフソン接合が超電導線路
の幅を横切って形成される。図１におけるＸ−Ｘ'の断
面図を図２に示す。図２において超電導薄膜のｃ面は任
意の位置で紙面に直交しているので、ｃ面と紙面の交線
を図２に示したが、ｃ面は段差の上面と下面ではいずれ
も基板表面に平行であり、同じ配向軸であるが、段差の
斜面ではｃ面は基板表面に直交し、配向軸は異なる。従
って、段差の上端および下端で配向軸が異なり粒界が形
成され、これがジョセフソン接合となる。従って、超電
導線路４では交点５、６で２つのジョセフソン接合の直
列接続体が形成されることになる。同様に超電導線路７
では交点８、９で２つのジョセフソン接合の直列接続体
が形成されることになる。一方、超電導線路１０は凹部
領域２と交わらず、迂回して配置されているのでジョセ
フソン接合は形成されず、超電導配線として機能するこ
とになる。従って、これよりレイアウト設計に何らの制
約も加えずに、ジョセフソン接合と超電導配線を同時に
得られることになり、工程数や集積性を著しく損なわず
に、多数の段差型ジョセフソン接合を含んだ複雑な酸化
物超電導回路であるＱＦＰを実現できることになる。On this insulator 1, an oxide superconductor YBa 2
A superconducting thin film made of Cu 3 Ox and having a thickness of 0.2 μm was formed. Further, the superconducting line 3 shown in FIG. 1 was formed by etching. A step is formed at the boundary between the recessed region and the non-recessed region, that is, around the rectangular ABCD,
The superconducting line 4 intersects this boundary at two points of intersections 5 and 6, and the superconducting line 7 intersects two points of intersections 8 and 9. Therefore, the two superconducting lines 4 and 7 both traverse the concave region 2 and divide the concave region 2 into three regions. Thus, at intersections 5, 6, 8, and 9, Josephson junctions are formed across the width of the superconducting line. FIG. 2 is a sectional view taken along line XX ′ in FIG. In FIG. 2, since the c-plane of the superconducting thin film is orthogonal to the plane of the paper at an arbitrary position, the intersection line between the c-plane and the plane of the paper is shown in FIG. Although they are parallel and have the same orientation axis, the c-plane is orthogonal to the substrate surface on the slope of the step, and the orientation axis is different. Accordingly, the orientation axes are different at the upper end and the lower end of the step, and a grain boundary is formed, which is a Josephson junction. Therefore, in the superconducting line 4, a series connection of two Josephson junctions is formed at the intersections 5 and 6. Similarly, the superconducting line 7
In this case, a series connection of two Josephson junctions is formed at the intersections 8 and 9. On the other hand, since the superconducting line 10 does not intersect with the recessed region 2 and is arranged in a detour, no Josephson junction is formed, and the superconducting line 10 functions as a superconducting wiring. Therefore, the Josephson junction and the superconducting wiring can be obtained at the same time without any restriction on the layout design, and a large number of step-type Josephson junctions are included without significantly impairing the number of processes and integration. The QFP, which is a complicated oxide superconducting circuit, can be realized.
【００１６】次に図３を用いて第２の実施例を説明す
る。本実施例は、単一のジョセフソン接合を作製した例
である。本発明の第１の実施例と同様にして、(１００)
ＳrＴiＯ3基板からなる絶縁体１の表面に長方形ＡＢＣ
Ｄの凹部領域２を形成した。凹部領域の深さ、すなわち
段差の高さはｈ＝０.２６μｍ、段差の角度はα＝６０
°とした。長方形ＡＢＣＤについては種々の大きさを検
討した。図３(ａ)、(ｂ)、(ｃ)は、凹部領域と超電導線
路の交わりの超電導線路に沿っての長さ、すなわち線分
ＡＢ、線分ＤＣの長さを順に０.９μｍ、０.６μｍ、
０.３μｍとした時の断面構造である。図３(ａ)、(ｂ)
では、対向する２つの段差の上端、下端にそれぞれ粒界
が形成されている。そこで、さらに凹部領域の面積を小
さくし、凹部領域と超電導線路の交わる領域の超電導線
路の進行方向に沿った長さを短くし、対向する段差の斜
面を近接させると、図３(ｃ)のように下面は近似的に無
視することができる。この時、上面と斜面のみ存在する
ことになるので、粒界は近接して対向した２つの斜面の
上端に形成され、直列接続ではない単一のジョセフソン
接合が得られることになる。本実施例では段差の角度α
＝６０°、段差の高さｈ＝０.２６μｍとし、この時、
凹部領域と超電導線路の交わりの超電導線路に沿っての
長さが０.３μｍであれば、単一のジョセフソン接合が
得られた。しかし本実施例の条件に限らず、粒界を形成
するためには段差の角度αは４５°以上であれば十分で
あり、さらに通常、酸化物超電導体ＹＢa2Ｃu3Ｏxから
なる超電導薄膜の膜厚は０.５μｍ以下であり、段差の
高さすなわち凹部領域の深さはその２倍以下、すなわち
１μｍ以下が適当であることを考慮すれば、本実施例の
結果より、凹部領域と超電導線路の交わりの超電導線路
に沿っての長さを２μｍ以下とすれば、良好な素子特性
を示す単一のジョセフソン接合が得られることになる。Next, a second embodiment will be described with reference to FIG. This embodiment is an example in which a single Josephson junction is manufactured. As in the first embodiment of the present invention, (100)
A rectangular ABC is formed on the surface of the insulator 1 made of a SrTiO 3 substrate.
D recessed region 2 was formed. The depth of the concave region, that is, the height of the step is h = 0.26 μm, and the angle of the step is α = 60.
°. Various sizes of the rectangular ABCD were examined. 3 (a), 3 (b) and 3 (c) show the length along the superconducting line at the intersection of the concave region and the superconducting line, that is, the lengths of the line segment AB and the line segment DC are 0.9 μm and 0 μm, respectively. .6μm,
This is a cross-sectional structure when the thickness is 0.3 μm. Fig. 3 (a), (b)
In, a grain boundary is formed at each of the upper end and the lower end of two opposing steps. Therefore, when the area of the concave region is further reduced, the length of the region where the concave region intersects with the superconducting line along the traveling direction of the superconducting line is shortened, and the slopes of the opposing steps are brought closer to each other. Thus, the lower surface can be approximately ignored. At this time, since only the upper surface and the slope are present, the grain boundary is formed at the upper end of the two slopes that are close to each other and a single Josephson junction that is not connected in series is obtained. In this embodiment, the angle α of the step
= 60 ° and the height h of the step is 0.26 μm.
If the length along the superconducting line at the intersection of the concave region and the superconducting line was 0.3 μm, a single Josephson junction was obtained. However, the present invention is not limited to the conditions of the present embodiment, and it is sufficient that the angle α of the step is 45 ° or more in order to form a grain boundary. Further, usually, a superconducting thin film made of an oxide superconductor YBa 2 Cu 3 Ox is used. Considering that it is appropriate that the film thickness is 0.5 μm or less and the height of the step, that is, the depth of the concave region is twice or less, that is, 1 μm or less, the result of the present embodiment shows that the concave region is If the length of the intersection of the lines along the superconducting line is 2 μm or less, a single Josephson junction exhibiting good device characteristics can be obtained.
【００１７】[0017]
【発明の効果】以上説明したように本発明の段差型ジョ
セフソン接合を含んだ酸化物超電導回路では、絶縁体表
面に形成された凹部領域を超電導線路が横断することに
よりジョセフソン接合が形成されるので、レイアウト設
計に何らの制約も加えずに、ジョセフソン接合と超電導
配線が同時に得られ、これより工程数や集積性を著しく
損なわずに、多数の良好な素子特性の段差型ジョセフソ
ン接合を含んだ複雑な酸化物超電導回路を実現できるこ
とになる。As described above, in the oxide superconducting circuit including the step-type Josephson junction according to the present invention, the Josephson junction is formed by the superconducting line traversing the concave region formed on the insulator surface. Therefore, the Josephson junction and the superconducting wiring can be obtained at the same time without any restrictions on the layout design.Therefore, the step-type Josephson junction with a large number of good device characteristics can be obtained without significantly impairing the number of processes and integration. A complicated oxide superconducting circuit including the above can be realized.
【図１】本発明の第１の実施例の酸化物超電導回路，Ｑ
ＦＰのレイアウト図。FIG. 1 shows an oxide superconducting circuit according to a first embodiment of the present invention, Q
FIG.
【図２】本発明の第１の実施例の断面構造の図。FIG. 2 is a diagram showing a cross-sectional structure of the first embodiment of the present invention.
【図３】本発明の第２の実施例の断面構造の図。FIG. 3 is a diagram of a cross-sectional structure according to a second embodiment of the present invention.
１・・・絶縁体、２・・・凹部領域、３、４、７、１０
・・・超電導線路、５、６、８、９・・・交点。DESCRIPTION OF SYMBOLS 1 ... Insulator, 2 ... Depressed area, 3, 4, 7, 10
... superconducting lines, 5, 6, 8, 9 ... intersections.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 樺沢 宇紀 東京都国分寺市東恋ケ窪１丁目280番地 株式会社日立製作所中央研究所内 (72)発明者 深沢 徳海 東京都国分寺市東恋ケ窪１丁目280番地 株式会社日立製作所中央研究所内 (72)発明者 高木 一正 東京都国分寺市東恋ケ窪１丁目280番地 株式会社日立製作所中央研究所内 (56)参考文献 特開 平１−211985（ＪＰ，Ａ) 特開 平２−211679（ＪＰ，Ａ) 特開 平３−35570（ＪＰ，Ａ) 特開 平３−228381（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) H01L 39/00 ZAA H01L 39/22 ZAA H01L 39/24 ZAA G01R 33/035 ZAA──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Uki Kabazawa 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Tokukai Fukazawa 1-1280 Higashi Koikekubo, Kokubunji-shi, Tokyo Hitachi, Ltd. In the Central Research Laboratory of the Works (72) Inventor Kazuma Takagi 1-280 Higashi Koikekubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory of the Hitachi, Ltd. (56) References JP-A 1-211985 (JP, A) JP-A-2-211679 (JP, A) JP-A-3-35570 (JP, A) JP-A-3-228381 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) H01L 39/00 ZAA H01L 39 / 22 ZAA H01L 39/24 ZAA G01R 33/035 ZAA
Claims (1)
性基板自体からなる絶縁体と、該絶縁体に接して形成さ
れた酸化物超電導体からなる超電導薄膜とを少なくとも
含んで構成される酸化物超電導回路において、該絶縁体
は表面に少なくとも1つ以上の凹部領域を含み、該超電
導薄膜は少なくとも１つ以上の超電導線路を含み、かつ
該超電導線路は該凹部領域とそうでない領域の境界と２
箇所以上で交わり、該超電導線路は該凹部領域を横断し
て２つ以上の領域に分割し、該凹部領域の深さは１μm
以下、かつ該凹部領域と該超電導線路の交わりは該超電
導線路に沿って長さ２μm以下であり、該超電導線路の
ｃ面が凹部領域の斜面で該基板の表面に垂直であり凹部
領域でない領域で該基板の表面に平行であり、該超電導
線路が該凹部領域を横断する横断部で単一のジョセフソ
ン結合を有することを特徴とする酸化物超電導回路。1. An insulator comprising an insulating thin film formed on a substrate or an insulating substrate itself, and a superconducting thin film comprising an oxide superconductor formed in contact with the insulator. In an oxide superconducting circuit, the insulator includes at least one or more recessed regions on a surface, the superconducting thin film includes at least one or more superconducting lines, and the superconducting line is a boundary between the recessed region and a region that is not. And 2
Intersect at more than one point, the superconducting line is divided into two or more regions across the recessed region, and the depth of the recessed region is 1 μm
Below, and the intersection of the concave region and the superconducting line has a length of 2 μm or less along the superconducting line.
The c-plane is a slope of the recessed area, perpendicular to the surface of the substrate, and
An oxide superconducting circuit, characterized in that the superconducting line is parallel to the surface of the substrate in a region that is not a region, and the superconducting line has a single Josephson bond at a cross section that traverses the concave region.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7149982A JP2790079B2 (en) | 1995-06-16 | 1995-06-16 | Oxide superconducting circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7149982A JP2790079B2 (en) | 1995-06-16 | 1995-06-16 | Oxide superconducting circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH098370A JPH098370A (en) | 1997-01-10 |
| JP2790079B2 true JP2790079B2 (en) | 1998-08-27 |
Family
ID=15486887
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7149982A Expired - Fee Related JP2790079B2 (en) | 1995-06-16 | 1995-06-16 | Oxide superconducting circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2790079B2 (en) |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01161786A (en) * | 1987-12-18 | 1989-06-26 | Toshiba Corp | Superconducting device |
| JPH07120822B2 (en) * | 1988-02-18 | 1995-12-20 | 日本電気株式会社 | Josephson device manufacturing method |
| JPH02211679A (en) * | 1989-02-10 | 1990-08-22 | Semiconductor Energy Lab Co Ltd | Substrate for manufacture of oxide superconductor thin-film |
| JPH0335570A (en) * | 1989-06-30 | 1991-02-15 | Mitsubishi Electric Corp | Quasi-plane josephson junction |
| JPH07101759B2 (en) * | 1990-02-02 | 1995-11-01 | 株式会社日立製作所 | Superconducting element |
-
1995
- 1995-06-16 JP JP7149982A patent/JP2790079B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH098370A (en) | 1997-01-10 |
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